1. Field of the Invention
The present invention relates to the field of well completion systems and methods, and particularly to a system and method for open hole well completion in a single trip.
2. Description of the Prior Art
The present invention provides a system and method for open hole well completion in a single trip. In the past, it has been necessary to make at least two trips into an open hole well in order to effect well completion. The need to run equipment into the well more than once involves additional time and expense which are obviated by the present invention.
In accordance with the prior art, well completion has typically involved multiple steps, i.e. trips into the well. In the first step, the packer is run into the hole and set, followed by conventional circulation and breaker soak. With the elimination of the filter cake, it is possible to lose fluid to the open hole. Therefore, a fluid loss control device is used, typically employing a frangible item which needs to be broken for production of the well. Following setting of the packer, the work string including the setting tool is removed from the well. The production tubing is then run into the well as the final step to prepare for production of the well.
In contrast to the prior art, the present invention utilizes a system which does not require that the production tubing be run into the well separately. Rather, the production tubing is assembled with the packer for the initial run into the well bore, and continuous coil tubing is thereafter used to open the well for production. The present invention thereby provides both time and cost advantages over the prior art methods involving multiple trips into the well. For example, running coil tubing into the well may take about four hours to complete at a cost of approximately $10,000. By comparison, running the second trip into the well in accordance with prior art methods can take twenty four hours, at a cost of $60,000.
The present invention also is distinctive in its use of an isolation sleeve which is installed inside the production screen at surface and thereafter controlled in the well bore by means of an inner service string. In contrast, the prior art has used systems which involve intricate positioning of tools which are installed down-hole after the gravel pack. These prior art systems are exemplified by a commercial system available from Baker. This system utilizes an anchor assembly which is run into the well bore after the gravel pack. The anchor assembly is released by a shearing action, and subsequently latched into position.
Certain disadvantages have been identified with the systems of the prior art. As previously indicated, prior conventional isolation systems have had to be installed after the gravel pack, thus requiring greater time and extra trips to install the isolation assemblies. Also, prior systems have involved the use of fluid loss control pills after gravel pack installation, and have required the use of thru-tubing perforation or mechanical opening of a wireline sliding sleeve to access alternate or primary producing zones. In addition, the installation of prior systems within the well bore requires more time consuming methods with less flexibility and reliability than a system which is installed at the surface.
There has therefore remained a need for an isolation system for well control purposes and for well bore fluid loss control which combines simplicity, reliability, safety and economy, while also affording flexibility in use. The present invention satisfies this need, utilizing an isolation system which does not require the running of tailpipe and isolation tubing separately. Instead, the present system uses the same pipe to serve both functions: as tailpipe for circulating-style treatments and as production/isolation tubing.